1 /* 2 * Memory fault handling for Hexagon 3 * 4 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved. 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 and 8 * only version 2 as published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program; if not, write to the Free Software 17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 18 * 02110-1301, USA. 19 */ 20 21 /* 22 * Page fault handling for the Hexagon Virtual Machine. 23 * Can also be called by a native port emulating the HVM 24 * execptions. 25 */ 26 27 #include <asm/pgtable.h> 28 #include <asm/traps.h> 29 #include <asm/uaccess.h> 30 #include <linux/mm.h> 31 #include <linux/signal.h> 32 #include <linux/module.h> 33 #include <linux/hardirq.h> 34 35 /* 36 * Decode of hardware exception sends us to one of several 37 * entry points. At each, we generate canonical arguments 38 * for handling by the abstract memory management code. 39 */ 40 #define FLT_IFETCH -1 41 #define FLT_LOAD 0 42 #define FLT_STORE 1 43 44 45 /* 46 * Canonical page fault handler 47 */ 48 void do_page_fault(unsigned long address, long cause, struct pt_regs *regs) 49 { 50 struct vm_area_struct *vma; 51 struct mm_struct *mm = current->mm; 52 siginfo_t info; 53 int si_code = SEGV_MAPERR; 54 int fault; 55 const struct exception_table_entry *fixup; 56 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE | 57 (cause > 0 ? FAULT_FLAG_WRITE : 0); 58 59 /* 60 * If we're in an interrupt or have no user context, 61 * then must not take the fault. 62 */ 63 if (unlikely(in_interrupt() || !mm)) 64 goto no_context; 65 66 local_irq_enable(); 67 68 retry: 69 down_read(&mm->mmap_sem); 70 vma = find_vma(mm, address); 71 if (!vma) 72 goto bad_area; 73 74 if (vma->vm_start <= address) 75 goto good_area; 76 77 if (!(vma->vm_flags & VM_GROWSDOWN)) 78 goto bad_area; 79 80 if (expand_stack(vma, address)) 81 goto bad_area; 82 83 good_area: 84 /* Address space is OK. Now check access rights. */ 85 si_code = SEGV_ACCERR; 86 87 switch (cause) { 88 case FLT_IFETCH: 89 if (!(vma->vm_flags & VM_EXEC)) 90 goto bad_area; 91 break; 92 case FLT_LOAD: 93 if (!(vma->vm_flags & VM_READ)) 94 goto bad_area; 95 break; 96 case FLT_STORE: 97 if (!(vma->vm_flags & VM_WRITE)) 98 goto bad_area; 99 break; 100 } 101 102 fault = handle_mm_fault(mm, vma, address, flags); 103 104 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) 105 return; 106 107 /* The most common case -- we are done. */ 108 if (likely(!(fault & VM_FAULT_ERROR))) { 109 if (flags & FAULT_FLAG_ALLOW_RETRY) { 110 if (fault & VM_FAULT_MAJOR) 111 current->maj_flt++; 112 else 113 current->min_flt++; 114 if (fault & VM_FAULT_RETRY) { 115 flags &= ~FAULT_FLAG_ALLOW_RETRY; 116 flags |= FAULT_FLAG_TRIED; 117 goto retry; 118 } 119 } 120 121 up_read(&mm->mmap_sem); 122 return; 123 } 124 125 up_read(&mm->mmap_sem); 126 127 /* Handle copyin/out exception cases */ 128 if (!user_mode(regs)) 129 goto no_context; 130 131 if (fault & VM_FAULT_OOM) { 132 pagefault_out_of_memory(); 133 return; 134 } 135 136 /* User-mode address is in the memory map, but we are 137 * unable to fix up the page fault. 138 */ 139 if (fault & VM_FAULT_SIGBUS) { 140 info.si_signo = SIGBUS; 141 info.si_code = BUS_ADRERR; 142 } 143 /* Address is not in the memory map */ 144 else { 145 info.si_signo = SIGSEGV; 146 info.si_code = SEGV_ACCERR; 147 } 148 info.si_errno = 0; 149 info.si_addr = (void __user *)address; 150 force_sig_info(info.si_code, &info, current); 151 return; 152 153 bad_area: 154 up_read(&mm->mmap_sem); 155 156 if (user_mode(regs)) { 157 info.si_signo = SIGSEGV; 158 info.si_errno = 0; 159 info.si_code = si_code; 160 info.si_addr = (void *)address; 161 force_sig_info(SIGSEGV, &info, current); 162 return; 163 } 164 /* Kernel-mode fault falls through */ 165 166 no_context: 167 fixup = search_exception_tables(pt_elr(regs)); 168 if (fixup) { 169 pt_set_elr(regs, fixup->fixup); 170 return; 171 } 172 173 /* Things are looking very, very bad now */ 174 bust_spinlocks(1); 175 printk(KERN_EMERG "Unable to handle kernel paging request at " 176 "virtual address 0x%08lx, regs %p\n", address, regs); 177 die("Bad Kernel VA", regs, SIGKILL); 178 } 179 180 181 void read_protection_fault(struct pt_regs *regs) 182 { 183 unsigned long badvadr = pt_badva(regs); 184 185 do_page_fault(badvadr, FLT_LOAD, regs); 186 } 187 188 void write_protection_fault(struct pt_regs *regs) 189 { 190 unsigned long badvadr = pt_badva(regs); 191 192 do_page_fault(badvadr, FLT_STORE, regs); 193 } 194 195 void execute_protection_fault(struct pt_regs *regs) 196 { 197 unsigned long badvadr = pt_badva(regs); 198 199 do_page_fault(badvadr, FLT_IFETCH, regs); 200 } 201